Carcinomas of the Bronchus

• Most common cause of cancer mortality worldwide for both males and females
• Incidence increasing with only 5% of causes cured
• Associations: cigarette smoking (90% of lung cancer cases), passive smoking, asbestos, chromium, arsenic, iron oxides and radiation

Signs and Symptoms

• Cough (80%), haemoptysis (70%), dyspnoea (60%), chest pain (40%)
• History of recurrent and slowly resolving pneumonia
• May complain of Lethargy, anorexia, weight loss
• Signs: cachexia, anaemia, digital clubbing, hypertrophic pulmonary osteoarthropathy, supraclavicular and/or axillary nodes
• Chest: consolidation (reduced aeration, coarse crackles), pleural effusion (reduced aeration, dullness to percussion)
• Metastasis: bone tenderness (bone), hepatosplenomegaly (liver), confusion, seizures, focal neurology, cerebellar signs (brain), peripheral neuropathy (peripheral nervous system)

Classification

• Based on histology
• Non-small cell lung cancer (NSCLC) – 80%
  • Squamous cell (35%): associated with PTHrP and hypercalcaemia
  • Adenocarcinoma (27%): most common type of lung cancer in people who don’t smoke, associated with anaplastic lymphoma kinase positive (ALK+), especially in the younger patients
  • Large cell carcinoma (10%)
  • Adenocarcinoma in situ (rare)
• Small cell lung cancer (SCLC) - 20%
  • Derived from endocrine cells (Kulchitsky cells – small dark blue cells)
  • Often secretes polypeptide hormones causing paraneoplastic syndromes e.g. ACTH – causing Cushing syndrome, ADH – causing SIADH
  • 70% has metastasis by the time of presentation
• Other lung tumours
  • Bronchial adenoma: rare, slowing growing, 90% are carcinoid tumours
  • Hamartoma: rare, benign, CT shows lobulated mass + calcification

Investigation

• CXR: pleural nodules, hilar opacification/enlargement, consolidation, atelectasis, pleural effusion
• CT or PET: to stage the tumour + guide biopsy
• Fine needle aspiration or brochoscopy: for tissue diagnosis
• Lung function test: to assess suitability for surgical treatment
• Radionuclide bone scan: if suspecting bone metastasis

Management

• Depends on TMN staging
• NSCLC
  • Lobectomy is treatment of choice if fit for surgery and potentially curative
  • Stage I, II, III → also radical radiotherapy
  • More advanced disease → chemotherapy +/- radiotherapy
• SCLC
  • Limited stage disease: surgery
  • Otherwise, chemo +/- radiotherapy
  • Palliative radiotherapy to help relieve bronchial obstruction, SVC syndrome etc.
  • For continued symptoms: consider tracheal stenting, cryotherapy, laser brachytherapy etc.

Prognosis

• NSCLC: survival 50% at 2 years if non-spreading at diagnosis, 10% if already spread
• SCLC: 3 months without treatment, 1-1.5 years if treated

Reference:

• Oxford Handbook of Clinical Medicine (10th Ed)
• UpToDate - Lung Carcinomas